ether was created without the goal of replacing bitcoin. It is rather a platform for decentralized applications, the so-called "smart contracts". so if the ether and wants to catch bitcoin, then only in price. but this is unlikely ...
I think that the probability that the ethereum will become the number one coin for capitalization is very high. In fact, this requires very little. Ether has repeatedly shown its potential for growth. I think that this year we will see something interesting.